Infection begins when the pathogen does what?

Infection begins when the pathogen enters the plant. This is the critical first step in the disease cycle, as it allows the pathogen to bypass the plant's natural defenses and establish itself within the host. Once a pathogen has entered, it can begin to exploit the plant's nutrients and resources, leading to further development of the infection.

While reproduction, growth in soil, and energy conversion are important processes related to pathogen life cycles, they occur after or outside the context of establishing an infection. For example, a pathogen may reproduce rapidly after it has successfully invaded the plant, but this reproduction is not the initial stage of infection. Similarly, a pathogen growing in the soil or converting energy is part of their survival and growth strategy, but these processes do not directly lead to infection unless the pathogen first enters a vulnerable plant host.